Error-free and error-prone lesion bypass by human DNA polymerase κ in vitro

Error-free lesion bypass and error-prone lesion bypass are important cellular responses to DNA damage during replication, both of which require a DNA polymerase (Pol). To identify lesion bypass DNA polymerases, we have purified human Pol kappa encoded by the DINB1 gene and examined its response to damaged DNA templates. Here, we show that Human Pol kappa is a novel lesion bypass polymerase in vitro. Purified human Pol kappa efficiently bypassed a template 8-oxoguanine, incorporating mainly A and less frequently C opposite the lesion. Human Pol kappa most frequently incorporated A opposite a template abasic site. Efficient further extension required T as the next template base, and was mediated mainly by a one-nucleotide deletion mechanism. Human Pol kappa was able to bypass an acetylaminofluorene-modified G in DNA, incorporating either C or T, and less efficiently A opposite the lesion. Furthermore, human Pol kappa effectively bypassed a template (-)-trans-antibenzo[a]pyrene-N-2-dG lesion in an error-free manner by-incorporating a C opposite the bulky adduct. In contrast, human Pol kappa was unable to bypass a template TT dimer or a TT (6-4) photoproduct, two of the major UV lesions. These results suggest that Poi kappa plays an important role in both error-free and error-prone lesion bypass in humans.